phrase usage - Making phone calls with someone

I know you are supposed to introduce yourself on the phone by saying something like "this is so and so", but how do you introduce yourself when you are calling with someone? Do you say

"This is A and B"?

But then I don't think that is grammatically correct. Should it be something like "we are A and B"?

Also, would this be a proper way to introduce yourselves?

"This is A, who had her appointment on Monday." (Although you are talking about yourself?)